Tuesday, January 22, 2008

Discussion About Campbell's The China Study

Melinda raised some points in her comment that I'm motivated to counter-comment on. It's lengthy, so I decided to post them here. The original post that she commented on was T. Colin Campbell Speaking On The Effect Of Animal Protein And Casein where I provided a link to Campbell's speech summarizing his book, The China Study.

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Melinda:

I just watched both videos (all the way thru) and found them quite fascinating. As a public speaker, Campbell's folksy manner may make him a *bit* of an imperfect messenger, as it leads him to speak in generalities that probably are easier to refute than hard numbers. But he obviously has hard numbers.

I probably should read the book, but the charts he shows are rather convincing, especially as they take into account the fact that some of the rural Chinese studied were in fact office workers rather than field workers. So the exercise factor is mooted to some extent.

And the issue of immigrants taking on the diseases of their adopted country (and diet) is compelling, especially in its relationship to genetic issues (which don't change when one moves).

The issue of soy & wheat protein vs. animal protein came across clearly as well, though w/ soy I personally think some forms of soy are not healthy.

The only part where I feel like I want some clarification (which I probably would get if I read the book) is the issue of total fat intake--if one, say, eats a diet w/ 20% fat comprised of olive oil, versus 20% from non-plant sources, for example, does one still avoid the Western diseases he speaks of? Or does he mean it needs to be less than 10% fat of any kind?

As a vegetarian getting a bit closer to veganism, I'm of course interested in these issues and am not going to take up meat-eating regardless. And I agree w/ him on the problem of toxins in fish (not to mention meat). But I would like to know more about fat as he explains it--I believe he said in the 40-min video that plant fats did not cause these diseases unless they were polyunsaturated fats. And he also said that cutting fat intake leads people, often, to increase their animal foods intake. Any clarification, Bix, would be welcome!

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You watched them! I didn't think anyone would have the inclination or patience. You have my respect.

I agree with you that Campbell's generalizations make him vulnerable. But for the body of evidence he was trying to communicate, I accepted his generalizations and continued to hear him out.

In the book he supports more of his statements. You can go to the studies he cites (which he does often) and investigate further (which I've done). But always, always, at some point, when you dissect something down to a little piece, out of context, you become vulnerable again.

That path towards understanding ... moving away from generalizations and towards hard data ... is something I learned in school, and had reinforced in industry. I used to believe it absolutely, "Show me the numbers!" In engineering, someone would shake a piece of paper at you and if the number was analyzed to three decimal points, well gosh, who could argue with that! (Unfortunately, the inputs were so gross, that is, so broad and arbitrary, "Oh... about 10 pounds", that it made a result to 3 decimal points absurd.)

I've changed. I now see that the path, not forsaking that it requires you to move away from a generalization and towards data, continues to move out again. You have to put all your pieces of data together and look at the whole picture. And never let go of your doubt, always question.

Campbell said it this way:

"It is quite easy to find a weakness or an aberrant observation in every single experiment. If executed and interpreted within the context of a larger worldview/hypothesis, each experiment gives direction as to what to do next, perhaps even suggesting a sharp turn in a new direction. If a larger truth is emerging, it seldom if ever depends on one experiment. Rather, it is a matter of accumulating evidence for a series of experiments, especially to see if the evidence is logically connected and consistent."

I think Campbell, in his book and in this speech, was trying to parse decades of work (both his own and others), to look at the whole picture. In my mind, he has something to offer in that. He's worth listening to.

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Regarding some points you raised:

I agree, that he looked at office workers does attenuate the exercise confounder to some extent.

Yes, that people who move develop the diseases of the place they move to ... does make you think that environment (including diet, but not limited to it) is influential ... very influential.

As to animal vs. plant proteins. Wasn't that interesting? Why do animal proteins appear to react differently in the body than plant proteins? I've experienced this with clients who had arthritis. I recommended that they try to replace some animal protein with plant protein, since antigens in animal sources were thought to aggravate joint inflammation. There was some benefit.

The fat issue. I loved that panel where he finally showed, near the end, that the correlation between fat intake and cancer may have been confounded. That high fat intake was strongly correlated to high animal protein intake. That it may not have been the fat after all, but the protein. Who knows if there may be an even stronger confounder. (Campbell wonders this too.)

From what I've put together over the years, I'm coming to think that fat has gotten a bad rap. That's a risky statement, because some people will run away thinking they can eat fat ad libitum, without effect. There is less of an effect for macronutrients when calories are low. But as calorie intake increases, the contribution of macronutrients plays a larger role. Another way of looking at that ... if you feed someone 500 calories a day as bread, they probably won't gain weight, or develop the chronic diseases related to weight ... diabetes, heart disease, joint inflammation, etc. But if you feed someone 2000 calories a day, 3000 calories a day as bread, then the macronutrient breakdown (how much fat, carbohydrate, protein) has a greater effect. The optimum amounts? Who knows? But it has to be said, also, that people respond differently to different diets. So no one way of eating will be the absolute best for everyone.

Also, as calorie intake goes up, the type of fat comes into play, as does the type of carbohydrate. These things are fluid and relative.

Personally, I don't think that a diet that provides 10% fat is a realistic goal, putting aside any possible health benefits. Even Ornish concedes this ... his 10% fat was for heart disease reversal, not for everyone. And pushing fat down that much, by default, has us eating proportionately more protein and carbohydrate. With what effect?

A diet that provides some of all types of fat, saturated (coconut oil, palm oil, as well as from animal sources), monounsaturated fat (olive oil), and polyunsaturated fat (omega-3s are polyunsaturated), in their cleanest, least-processed forms (minimal heating, minimal chemical extraction) is probably the best.

I came away from Campbell's talk, and writing, thinking that there may be a justified positive correlation between animal protein (at high levels of intake, as I noted above) and chronic disease. No one has proven this. But there does appear to be, in my eyes, a foundation for this thinking.

One last thing, a caveat of sorts. And this goes back to my fifth paragraph up there. You have to look at the whole picture, the whole diet, how these macronutrients (and micronutrients) are coming packaged.

This was where the fat correlation broke down. We weren't looking to see that fat was coming packaged, oft-times, with animal protein (and maybe something else).

This was where the carbohydrate recommendation broke down. We weren't looking to see that carbs were being consumed, oft-times, as over-processed, nutrient-poor derivatives.

This may be where the casein correlation breaks down. Maybe we aren't looking to see how the casein comes packaged (denatured? a processed derivative? with calcium? etc.)

Now that I've talked too much and lost everyone, I'll stop. My next post will be pictures.

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Photo of an aluminum plate, fork, and spoon. Made from scrap metal. Used by a family who fled Estonia after WWII and settled into a Displaced Persons camp in Germany. Source: The Migration Heritage Centre of New South Wales.Now we just have to figure out what to put on it.